Internet Protocol television (IPTV) is a system through which Internet television services are delivered using the architecture and networking methods of the Internet Protocol Suite over a packet-switched network infrastructure, e.g., the Internet and broadband Internet access networks, instead of being delivered through traditional radio frequency broadcast, satellite signal, and cable television (CATV) formats.
IPTV services may be classified into three main groups: (1) Linear television, with or without interactivity related to the current TV show; (2) Time-shifted programming for catch-up TV (replays a TV show that was broadcast hours or days ago), and start-over TV (replays the current TV show from its beginning); and (3) Video on Demand (VOD) for browsing a catalog of videos, not related to TV programming.
IPTV is distinguished from general Internet-based or web-based multimedia services by its on-going standardization process, e.g., European Telecommunications Standards Institute, and preferential deployment scenarios in subscriber-based telecommunications networks with high-speed access channels into end-subscriber premises via set-top boxes or other customer-premises equipment.
Personal Video Recorder (PVR) is a generic term for a device that records television data in digital format. For example, a PVR may encode video data in MPEG-1 or MPEG-2 format and store the data in a hard drive. Common functions of a PVR allow the subscribers to record, playback, fast forward, rewind and pause the playback of content.
Additionally a PVR provides an ability to instantly jump to any part of a program without having to rewind or fast forward the data stream. The PVR function can be hosted locally by the STBs (LPVR) or externally by network functional entities, Network Personal Video Recorder (NPVR).
For NPVR systems, it may not be practical for the network service provider to maintain a copy of a PVR program on a service provider server or storage device for a single or a limited number of relatively few subscribers. In some markets, network personal video recorder, NPVR, solutions may store a single copy of a recorded program and share it amongst all subscribers who had intended to record it. This implies that the system must maintain a list of subscribers associated to each personal video recording, PVR. The system will never purge a recorded program as long as there is at least one subscriber who still has the PVR as part of their recording library.
Thus, in systems with a large number of subscribers, it is likely that a system may never be able to purge or delete any of its network recorded programming because there will likely always be at least one subscriber who still has the programming as part of his recording library. It may be impractical for the NPVR system to maintain a recording in a central server for a single subscriber or a few subscribers.